Spatial interactions between trees influence forest community succession. The objective of this study was to investigate how shifts in composition and proximity tree species affect stand development over time mixed systems. At six locations across the Fishlake National Forest, Utah, USA, stands where facilitation has been documented previously, tree-ring samples were collected from aspen subalp...

the understanding of the dynamic behavior of distillation columns has received considerable attention because distillation is one of the most widely used unit operations in chemical process industries. this paper reports a dynamic simulation study of the possible distillation columns sequences of dew pointing unit in the second phase of south pars gas refinery. in this unit, three columns are u...

Snow ablation modelling at the stand scale must account for the variability in snow cover and the large variations of components of energy transfer at the forest ̄oor. Our previous work successfully predicted snow ablation in a mature jack pine stand by using a one-dimensional snow process model and models predicting radiation below forest canopies. This work represents a second test of our bas...

The photoperiod is an important environmental signal for plants, and influences a wide range of physiological processes. For woody species in northern latitudes, cessation of growth is induced by short photoperiods. In many plant species, short photoperiods stop elongational growth after a few weeks. It is known that plant daylength detection is mediated by Phytochrome A (PHYA) in the woody hyb...

Although many species of bats select roost sites in large trees that are in open areas, intraspecific variation in roost-site selection may exist. We collected data on the roosting behaviour of little brown bats in the Cypress Hills, Saskatchewan, to determine the extent of intraspecific variation in roost-site selection. In addition, we examined the thermal microclimate of the tree-roosts sele...

From bacteria to multicellular animals, most organisms exhibit declines in survivorship or reproductive performance with increasing age ("senescence"). Evidence for senescence in clonal plants, however, is scant. During asexual growth, we expect that somatic mutations, which negatively impact sexual fitness, should accumulate and contribute to senescence, especially among long-lived clonal plan...

BACKGROUND Previous studies have shown that plants often have species-specific effects on soil properties. In high elevation forests in the Southern Rocky Mountains, North America, areas that are dominated by a single tree species are often adjacent to areas dominated by another tree species. Here, we assessed soil properties beneath adjacent stands of trembling aspen, lodgepole pine, and Engel...

STUDY DESIGN Randomized controlled trial. OBJECTIVE The aim of the study was to compare and contrast the restrictiveness and tissue-interface pressure (TIP) characteristics of 2 standard and 2 adjustable cervical collars. SUMMARY OF BACKGROUND DATA This study compared the restrictiveness and TIP of 4 commercially available cervical collars (2 standard and 2 adjustable). Adjustable collars o...

Concentrations of cellulose, lignin and nutrients in the stemwood of four clones of 7-year-old hybrid aspen (Populus tremula L. x P. tremuloides Michx.) were studied on 50 permanent experimental plots established for the afforestation of abandoned agricultural lands in Estonia. Quantitative evaluation of hybrid aspen chemical components indicated a relatively high cellulose and low acid-insolub...

Increasing concentrations of atmospheric carbon dioxide (CO2) and tropospheric ozone (O3) have the potential to affect tree physiology and structure, and hence forest feedbacks on climate. Here, we investigated how elevated concentrations of CO2 (+45%) and O3 (+35%), alone and in combination, affected conductance for mass transfer at the leaf and canopy levels in pure aspen (Populus tremuloides...